Irradiation of lubriating oils



United States Patent 3,153,622 an: i ADTATEQN 0F LUERICATHNG 0115 Earl ll. Humphrey, Verona, and .ieseph .l. McGrath, Monroeville, Pan, assignors to Gulf Research 8; Development Qompany, Pittsburgh, Pa, a corporation of Delaware No Drawing.

Filed (Bet. 27, 1959, Ser. No. 840,895 2 Claims. (Cl. 204-154) This invention relates to procedure for preparing an improved lubricating oil and in particular an improved oil for lubricating aircraft turbines and the like.

Lubricating oils which are presently available are not entirely satisfactory for use under severe conditions, particularly under high temperature conditions. The United States Air Force has required that oils for certain uses such as aircraft turbines meet specifications set forth in Specification MIL-L-9236A. This specification includes a test generally known as the panel coking test and measures the tendency of a lubricating oil to deposit coke at high temperatures. Few lubricating oils give satisfactory coke panel tests.

This invention has for its objective to provide improved lubricating oils. A still further object is to provide procedure for preparing lubricating oils having a low tendency to deposit coke during panel coking tests. A still further object is to provide an improved lubricating oil having a viscosity in the range between about 50 and 150 S.U.S. at 210 F. Other objects Will appear hereafter.

These and other objects of our invention are accomplished by subjecting a lubricating oil having a viscosity between about 50 and 150 S.U.S. at 210 F. and which has been treated with hydrogen to the influence of ionizing radiation of between about 0.001 and 10 watt hours per gram of said lubricating oil. i

The charge stock employed in our process may be derived from any type of petroleum such as Pennsylvania, MidContinent, West Coast, Middle-East crudes, etc. The charge stock must, after the hydrogen treatment, have a viscosity between about 50 and 150 S.U.S. at 210 F. The viscosity of the starting material prior to the hydrogen treatment must be selected so that the product, after the hydrogen treatment, will have the required viscosity of between about 50 and 150 S.U.S. at 210 F. Mild hydrogen treatment does not alter the viscosity of a lube oil stock to a great extent and when such hydrogen treatment is employed, the viscosity of the charge to the hydro gen treatment may be about the same as the required viscosity for the hydrogen treated product, i.e. between about and 150 S.U.S. at 210 P. On the other hand, many hydrogen treatments result in moderate or even extensive reduction in the viscosity of the hydrogen treated product a and in such cases the viscosity of the charge to the hydrogen treatment must be proportionately higher so that the product will have the required viscosity after the more or 1 less extensive lowering of viscosity during the hydrogen treating. The charge stock having approximately 50 to 150 viscosity at 210 F. need not be a purified fraction. Thus it is entirely satisfactory to charge to' the hydrogen tween about 200 and 10,000 p.s.i.g.; a temperature between about 400 and 850 F; at a space velocity between about 0.1 and 16 volumes of charge stock per volume of catalyst per hour; and at a hydrogen recycle rate of between about 400 and 20,000 standard cubic feet per barrel of charge. One known method of hydrogen treating lubricating oils is a mild type of operation to effect decoloration and hydrogenation of easily hydrogenated materials such as olefins. This procedure gives very little if any improvement in viscosity index and little if any change in viscosity. This mild operation is carried out at a pressure between about 200 and 2,000 p.s.i.g., at a temperature between about 450 and 750 F, at a space velocity between about 0.1 and 8.0. Any hydrogenation catalyst may be used such as nickel, cobalt, platinum and oxides and sulfides of group VI and group Vii metals such as molybdenum, tungsten, nickel, cobalt,

etc., oxides and sulfides or mixtures thereof. Porous supports may be used. Such procedure may be used to prepare an improved lubricating oil in accordance with our invention.

Another known method of hydrogenating lubricating oils is more severe than the above discussed hydrogen.

treatment. In this process the objective is not only to hydrogenate easily saturated materials such as olefins, but also to eifect a more or less extensive hydrogenation of aromatics. In this type of process a moderate improvement in viscosity index and slight reduction in viscosity is also obtained, indicating a certain amount of hydrocracking. This process is carried out in the presence of mixtures of a sulfide of a metal of the iron group mixedwith a sulfide of a metal of group VI of the periodic systern. These catalysts may be supported or unsupported on porous carriers. In the event a supported catalyst is em-. ployed, the carrier may be activated alumina, pumice, silica-alumina mixtures, etc. Pressures usually employed are about 1000 to 5000 p.s.i.g., temperatures between about 650 and 825 F. at a space velocity between about 0.1 and 4.0 This type of processmay also be used in accordance with our. invention.

index and viscosity of the charge stock. In this type of process the same catalysts may be employed that are mentioned in connection with the second type of hydrogen treatment. Pressures employed are between about 1750 and 10,000 p.s.i.g.; temperatures are between about 735 and 825 F; and space velocities are usually between 0.4 and 1.5. One aspect of this last mentioned type of process is the preparation of multigrade lubricating oils. In the event such a product is desired, the charge stock should have a viscosity index between about 60 and 100. We prefer to utilize as charge stock to the ionizing radiation a lubricating oil which has been subjected to a hydrogen treatment of the second or third type discussed above.

Certain aspects of the above described hydrogen treatments are described in United States patent application Serial No. 622,312, filed November 15, 1956, Beuther and Peterson, now Patent 2,917,448, and in United States patent application Serial No. 676,039, filed August 2, 1957, Beuther, Henke and McKinley, now Patent 2,960,458.

The hydrogenated lube oil stock may be subjected to the influence of the ionizing radiation in any desired manner. For instance, the lubricating oil may be pumped lfthrough a tube or pipe which is transparent to the ionizing radiations and which is exposed thereto. Alternatively,

the hydrogenated lube oil stock may be caused to flow by gravity, preferably in the form of thin film over a surface which is subjected to the influence of the ionizing radiation. Another satisfactory method is to place the lube oil in reservoirs or pans and convey these reservoirs through the ionizing radiations by means of an endless Patented Get. 20, 1964 7 3 belt or the like. The exposure to the ionizing radiation should be kept within the limits described above, i.e. between about 0.001 and 10 watt hours per gram of lube oil stock and preferably between about 0.003 and 3.0

a very high intensity of beta and gamma radiation but a very short half life. These gases possess about one percent of the total fission energy. The gases are chemically inert and therefore would not form undesired side reac- Watt hours per gram. We have found that the viscosity tion products. of the lube oil stock begins to increase rapidly at above Example watt hours per gram and therefore we prefer to keep I the ionizing radiation exposure below this value and prefhydfotreated f fir Q p 1n the manner erably between about .003 and 3 Watt hours per gram. scribed below, having a vlseoslty 0f 9 S115- at The radiation may be carried out at any desired tempera- 10 and an hnhlfdfegehated Teslduum hevlng shhstahtl'fllly h ture or pressure. Thus any temperature from 0 K. up e Vlseesfty e compared h and after to just below the decomposition temperature which usually tloh- The {Yfadlahoh Was carried out y P P the is about 700 F. may be used. The pressure does not sample of 011 through a glass tube exposed to a beam of affect the reaction and therefore may vary from the lowest electrons from a 3-m11110I1 Volt Y de Graafi? q obtainable reduced pressure up to the highest obtainable a F e of 4 t0 5 gallons P mlhute uhtll the lfldleated pressure AS a ractical matter e prefer to employ irradiation exposure had been delivered. The properties about ambient temperature d pressure, of the hydrotreated residuum are given in column 1 of Ionizing radiations can be obtained, for example, using 3 foluiwmg table Properties of the non'hydroglm' radio isotopes, nuclear reactors or high energy particle reslduum are i m 5 the acwmpanymg accelerators. Examples of radio isotopes which can be The prpperlles of the Irradiated hydrotreated used are cobalt 60 for gamma rays and strontium 90 for resl l are m columns 3 and of i accom' beta rays. Operating nuclear reactors of intermediate panymg table fl the profimegof the lrradlated or full power size can be used as a source for either hydroggnfited residuum are gwen In column 6 of the gamma rays or neutrons or both. Particle accelerators companymg such as the cyclotron, bevatron, synchrotron, Van de These Venous Samples were then suhleeted to a G fif or X hi can 1 be used, modified Panel Coking Test as described in paragraph In some instances Where it is desirable to expose the Of Speclfieatloh The apparatus il to f t or hi h energy neutrons only, d i h used for the Panel Coklng Test is described in Detailed stantial absence of beta and gamma radiation, the irradia- Handbook on Test Procedures in PP of Thfhol'et and tion can be conducted outside of the reactor using a col- 3O Turbepmp Luhllcahtsr March 1957, Wright limated beam of fast neutrons. Such a coliimated beam velophleht cemef- The medlfied Piece/(hire used in t s of fast neutrons can be obtained, for example, as described e i (infers Om thahdeserihed in the reference y in US. Patent No. 2,708,656 to Enrico Fermi and Leo that (1) y eheugh 011 (Whleh 1S Often a a l only Szilard, by inserting a hollow shaft or tube into the In small lf) 1S Placed 1n the reservoir to p the central i of h reactor, Gamma rays can be sump at the required level during the test period, and (2) screened from h f t neutron b by means f a the edges of the panels are not scraped to remove coke. sheet of bismuth metal extending across the path of the The Pehe1 depeslt Welghts listed in the ta l Show been clearly the advantages of the instant invention. The Aneutron-free radiation source can be obtained directly data in the table 8180 w t at t e irradiation of the from a homogeneous reactor by separating the radioactive 4O unhydrogehated Oil resulted in a Severe increase in fission gases, xenon and krypton, from the reactor core posit weight. Several of the control and test samples were by conventional or modified gas-liquid separating means. also subj t M L-9 36 x dati n test as Set A continuous supply of the radioactive fission gases could forth in the table. The results of these oxidation tests be obtained from such a reactor. The fission gases have show that the irradiated and hydrotreated oil was not Hydrotreated Residuum Unhydro- 101 viS./210 F. genated Residuum Column Number 1 2 3 4 5 6 Irradiation Dosage (watt hours per gram) 0 .0278 0 278 2.78 0 0. 27s Inspections:

Gravity, API 29.8 29.1 25.0 27.2 27.1 Viscosity, kinematic, es.-

100 243 246.8 324.8 14,904 244.5 311.0 210 F 20.81 21. 03 25.79 583.6 19.91 23.80 Viscosity Ind 107 106 108 121 101 103 Color, D1500 1.5 2- 3.5 5.5 3 3 Flash, 550 550 515 420 555 550 Fire, F--- 000 520 500 Pour, F +5 +5 0 +20 0 Neutralization Vaiue- TotaiAcid No. D664 0. 04 0.12 0. 05 0. 0.01 0.08 Panel Coking Test (700 F., 8 hrs Coke deposit, mg a 1, 238 84 b 374 n 90 d 362 500 F. Oxidation Test of Spec. MIL- L9236A, 48 hrs., 600 F., 5 liters/hr. dry air per mi. oil:

Increase in 100 F., cs. vis., percent 129 179 235 Increase in Total Acid No- 3. 48 3. 11 3. 87 3. 70 Weight change of metals, mg./

Mg- +0.03 0. 05 +0. 04 +0. 04 +0.01 0.21 0 C11 0. 01 0. 01 0. 02 greet +0.03 +0. 01 +0.03 +0.03 Ag +0.01 +0.01 0.03 +0.01 Ti... +0.01 0. 01 0.03 0.01

b Average of 4 tests. 0 Average of 13 tests. iiverage of Average of 5 tests. 2 tests.

(All tests were included in determining the average.)

harmfully afiected in regard to its oxidation characteristics.

The hydrotreated oil used in the above example was obtained by subjecting a deasphalted Ordovician residuum to treatment with hydrogen at a pressure of 3,000 p.s.i.g. at a temperature of 715 F., using a space velocity of 0.5, and an hydrogen recycle rate of 5,000 s.c.f./bbl. in the presence of a nickel-tungsten sulfide catalyst. The non-hydrogenated residuum used in the above example was obtained by subjecting a deasphalted Ordovician residuum to treatment with aluminum chloride. The irradiations were carried out at approximately ambient temperature.

What we claim is:

1. The process for preparing a lubricating oil having a relatively low tendency to deposit coke as determined by the Panel Coking Test, which process comprises subjecting a hydrogenated lubricating oil which has a viscosity between about 50 and 150 S.U.S. at 210 F. to ionizing ionizing radiation of between about 0.001 and 10.0 watt hours per gram of hydrogenated lubricating oil at about ambient temperature and pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,905,606 Long et a1 Sept. 22, 1959 2,951,022 Hartzband et a1. Aug. 30, 1960 2,954,334 Stoops et a1 Sept. 27, 1960 2,990,350 Natkin et al June 27, 1961 3,043,759 Read et a1 July 10, 1962 3,058,896 Nahin Oct. 16, 1962 

1. THE PROCESS FOR PREPARING A LUBRICATING OIL HAVING A RELATIVELY LOW TENDENCY TO DEPOSIT COKE AS DETERMINED BY THE PANEL COKING TEST, WHICH PROCESS COMPRISES SUBJECTING A HYDROGENATED LUBRICATING OIL WHICH HAS A VISCOSITY BETWEEN ABOUT 50 AND 150 S.U.S. AT 210*F. TO IONIZING RADIATION OF BETWEEN ABOUT 0.001 AND 10.0 WATT HOURS PER GRAM OF HYDROGENATED LUBRICATING OIL. 